Tool for inserting screw thread linings



Feb. 5, 1952 J. o. FoRsTl-:R

TOOL. FOR INSERTING SCREW THREAD LININGS Filed May 27, 1950 I N l "EN TOR. "Torsifr i. A A a Patented Feb. 5, 1,952

TOOL FOR INSERT-ING SCREW THREAD LININGS John 0. Forster, Long Island City, N. Y., assignor to Heli-Coil Corporation, Queens County, N. Y., a corporation of Delaware Application May 27, 1950, Serial No. 164,779

7 claims'. (C1. 11i- 1) which the tool essentially comprises a mandrelV rotatable .in a sleeve and projecting therefrom vl Withboth its ends.

The one end of the mandrel is provided with an axial slot to receive therein the tang of the coil to which "the mandrel may be applied fromtheinside thereof, and the end of the sleeve adjacent the slot is provided with an interior taperv against which. the tangless Y end of the coil can bear, while the mandrel is prevented from shifting axially with respect t`o the sleeve. The mandrel of the tool according to the Imentioned application has several pre-'- determined positions in axial relationship with respect'to the sleeve in order to adapt it to 'coils of different lengths.

The present invention aims to 'improvethe mentioned type tool and to render it useful for inserting a coil to Van accurately adjusted depth from the surface of the member the interior threading of which is to be lined. v

` Another'obje'ct of the inventiton is the provision of means releasably attachable 'to aV tool of the mentioned type for facilitating the contraction of a coil during its insertion.

.r Further objects andl details of the invention will be apparent from the description given hereinafterV and the 'accompanying drawing il- ;1 lustratingan embodiment thereof by wayof example. In the drawing t 'Fig'. 1 is alongitudinal cross-section ofv atool according tothe invention as4 applied to alwire lcoil. during its insertion integran `threaded member,

' interiorly Fig. 2 is a modified portion of the tool, :and

- f Fig. 3 is a side elevation of the tool of Fig. 1

with an attachment for contracting a coil .prior to. and during its insertion, shown in a longitudinal cross-section.

Referring-.now to the drawing, the tool illustrated in Fig. 1 comprises a mandrel in genral denoted by I0. The upperr end 'o'f the mandrel is exteriorly to a tool for inserting, into an interiorly threaded member, a screw thread lining which consists of a wire coil, pro vided with a tang for the application 'of angine A tool of the type here under con-fA 2 Inner diameter of a coil to be inserted with .the aid of the tool, is provided with an axial-slot 'I4 of substantial length. The mandrel is freely rotatable in a sleeve body I5,V the inner surface I 6 of which is cylindrical and of a diameter similar to the outer diameter of the mandrel threading I2. The lower portion I1 of the sleeve may be of a, reduced diameter and has an inner surface I6' which guides the mandrel portion I3. It is provided withaninner taper I8 which may extend from the outer circumferential surface of the sleeve portion: I1 to its inner surface I5. However, for' a; reason to be 'explained hereinafter, it is advisable-to avoid a sharp edge wheretheeouter surface and the tapermeet and to provide for at least a vnarrow rounded or plane ring zone I9 which mayor may not project axially from the taper, as the-ring zone I9' projects in Fig. 2 from the taper l'of'the sleeve end I1. The other end of the sleeve 'forms an axially extending rim 2l) continued in an inwardly projecting flange 2I. This flange engages in a peripheral groove 22 of a nut 23 which is screwed on the ithread `I 2 of -the mandrel I0 and bears with its lower end portion 24 on the top face 26 of the sleeve surrounded by the rim 20. In the production, the flange 2l may originally be an axially extending portion of the rim 20, to be turned inwardly intdthe groove 22 by a suitable operation, e. g.y by'rolling. Whereas the upper portion of nut 23 may have any desired cross-sectional shape suited toform a safe grip, the lower portion 24 and the groove 22 have circular -contours.v Consequently the nut 23 is flxedto the sleeve against relative movement inan axial direction but can readily turn in relation thereto'. Means such as the stop nut 25 v,are provided to secure the nut on the mandrel in any adjusted, position;

When the interior thread 3D of a member 3I is to be lined with-a wire coil 32 having a tang 33, first the coil is slid over the mandrel end so that the tang 33 engages in the slot I4 and the opposite end of the coil bears against the tapering face I8. The slot I4 should be of such a length that the tang is freely movable therein in an axial direction without ever abutting against the bottom of the slot. This is necessary to prevent an undesirable .bending 'of the tang during the insertion ofv the'coil. YBy turning the nut 23relatively to the mandrel, the latter will be adjusted relatively Vlto *the sleeve according fto the desired depthto which :the coil'is to be inserted below the surface-35 ofthe threaded'member-'31. If -itlisfdsired-,that n'ally theupper end face of the coil is below the surface 35, e. g. a. distance a, then, correct adjustment is attained, when the distance b of the inner edge 34 of the tang 33 from the end face 36 of the mandrel is equal to the distance a plus the distance c which is that of the upper end face of the coil from thefedgebrringfzone e'I 9 fthe sleeve. "By tighteningthe stop nut 25.on nut'23 the latter will be secured in its adjusted position with the result that the mandrel together with the nuts;

Theff'contactrfrb'etween* the'V 'coil tendtand the itaperfwill"bemaintainedfuntil Vthe coili'is 'screwed :tf'into'f ithethreadz-:so deeplthatthe edge' 'or'iring sfzone 219 'abats fagainstthe surface 35 of 'member I3 l'. `its. has.' beenftmentioned'ihereinbefore; a rig-'zoned 9 ispreferredftoa sharp edgeiinor'der .to'avoid damage to-rthel'surtac 35ifpyinadvertancearrexcessive pressureiisapplied tothe sleeve.

Zil31943 and? onventiohally denoted' Fas' ai 'pre- Winder tool. TFigithere'iis aitooltccoidingIto-:Eiga Pand in enerall denoted 'by- 40,-1fcompris`ing theimandrel il 0 wi'thfitsislot yil flaiand nuts a2 and i2 5 in 'engage- .iment with fthemiandrei*.':threadl I2 Iaridf'secured zfagainstraxial'zmovement? to: the sleeveV 'body 'l5 ithediametri'cally-v reduced *endA portion` l1 of:

'wliicneis-1providdf'f`withltthe interiori .endfitaper v d8. The; attachment ringgeneral de`noted.;:by4 4 I f'coniprises' aflillow:faz-.vinidrical:` portion :42.1.1115: an :jnnerldiameter;corresponding. tol :.the-f .outer div:s.:airl'et'erlf:of :the sleeveiwbddygel5%:and of'consider` F blyei-greater 'len'gths'than the flatter-'fwhichnis .a freely rotatable "andi axially. shiftable I in portion ,f42...f Any.` .suitable -and vl'son-ventional means .may -befusedtorconnectvthe attachment 4 lsdetachably tot thefiOQlffi Softhat. the-mentioned :relativerL Vturnedj ande thereby; lfacilitate :ithe "screwinglin l 1to0 uiscrosedjinin Silea-tent;.2;3i6pzziror-ApiiiV n 'fthe iinustratedl:embodimentof 4 movability of the one in relation to the other is insured. However, it is desirable that no external means are required to accomplish the attaching and detaching operations. For this 5 purpose, the upper end of the portion 42 is provided with an interior peripheral groove 43 hav- :1:'inga`spring' f'ring 44flemrbedddftheein which .islightlyprejeets beyond the inner^`cylindrical surface of the portion 42. Sleeve body I5 is 105? provided with a tapering face zone 46 Where it is ...joined with the.reduced portion l1, and with anthe tapering face zone 41 near its other end. When pushing the attachment 4| on the sleeve =body1|5,'"thetaper 46 will expand the ring 44 l5" which can 'contract to its original diameter when 'it passe'sthe'taper 41. The latter acts in a similar #Way.fonftheringwhen the attachment is to be removed from the tool 4D. It'will be noticed that`the taper 4B is steeper than the taper 41. In consequence, onlyla small force is required .fto fattachpart 4l ito.' 48;Whereas alvery apprecifable force Tis.: needed .to 'separateithei parts'rom :.'e'achi other." This A.fis desirable: in .order .to-.avoid their separation-if.; duringV theizuse the partffw 25` iisrap'idiy pulled'upwards in relation A.topart- -4 l'. ITPortion 42.h`as aninterior bottom sh'oulderf48 which: may be` beveled asY shown: and: which? has an Vopening 49 off aidiamet'er. correspondingito 1 "thefsleeve portion jI'l .so thatfth .latterv canlbe 30.. projected therethrough. 1 The fwall of. iportiorr 1lll.

f :is exter'i'dedv beyondthatzshoulder `48; andlthisexx-tension"` 53 ends'. intsa. foot 5 Iioppositetto: and spacedzrom theopening .49. iiExtension;5ft is Lsemi-circular:inzlcross-section andfoan .inner 35 Y diameter: corresponding ato.: :theliopeinngi :49' fand its length :is :such'y .that there: is. sufficient-space fbetween shoulder 48.: andi the ,foot-Slaloriithe I insertion of the f longest. vcoilforf'which "the tool :iis: destined. The .footzisg'providedv Witln anfin-l ner thread 52..:coaxial withfthez'tubular. portion `v42 and-.of a pitch' accordingztoithat:offy a lcoil tobe 'insertedfwithlthe :aidi:of-:the1tool. The thread .tapers Nfrom: afldiameter 'corresponding-ato the outer diameter of a coil-inf-its:iireeJstatefto 'l5V a diameter to whichfitfisintendedato contract thatlcoil. It: -mayfloej provided ywithiny .thewfoot material.proper.'or,- preferably,.in aseparatepiece 1. '.531A whichfis pressedand secured. in.the1foot.:.n any event, a shoulder: 54 is formedafadjacentithe 50.. .fthreadY 52 where-it is 'widestagainst Whichlshoulder: the {.sleeve portion'. .l1 can e abut with.. ,fring. .zone- 19'1 when the .part-40 lisrsl'iifted"V with respect to part 4 I=in1thexdirection ofiootsuSl.

,'Insorderfto-v adjust.thetoolflifor inserting a 5,5 s coil to: a :desired depth z underfthe 'surface' from -'whichathe threadv A-to :be v'lined:.extends'f .'intoi' a .memben .1 partV .4 will'. fbeie .shiftedin relations-itc part 4l so that zone-:ISrablitsfagainsirlshoulder i954 and thelslotted mandrel :end:v :proj ects through or/:the 'foot 5 Ifian'd; beyond-fits.: bottom surface: 55. By iturninginut 23 on '.'thermand-rel after.Y nut 225 has been loosened, and While -'thenpartsand V4| vare"ini'the mentionedi'relative positioni. the distance'iofthe facerSBSofthe:.projected-inan- .-tracted to itsposition:ofv Eig...3 whereupon al-:wire ...coil may be: placed' with-fitsk tangedend ion-shoulder fbetweenith'effoot- Lfandshaulder can be brought into engagement with the mandrel slot so that the sleeve taper I8 bears on the opposite coil end. Holding part BI stationary and turning the mandrel in the proper direction will screw the coil into the thread 52, simultaneously contracting its leading portion owing to the taper of the thread. It is immaterial whether during the turning of the mandrel in relation to the part 4l the sleeve turns with the mandrel or whether the mandrel turns in the sleeve. When the leading coil end in its contracted state starts to project from the lower foot face 55 the tool with the coil will be brought into registry with the threaded hole to be lined, face 55 vbearing on the surface of the member provided with that threaded hole. Continued turning of the mandrel will, then, screw the coil in. When in the course of this operation, face I9 reaches shoulder 54, the tang will start to slide out of the mandrel slot as hereinbefore described and will be free when the coil is in its desired position, whereupon the tool can be withdrawn.

It will be apparent to those skilled in the art that many alterations and modifications of the illustrated structure are possible without departure from the essence and spirit of my invention which for that reason shall not be limited but by the scope of the appended claims.

IV claim:

1. A tool of the type described comprising a mandrel having one end axially slotted, its other end formed for the application of a torque, and an intermediate threaded portion, a sleeve surrounding said mandrel intermediate its ends and having the one of its end faces from which said slotted mandrel end projects inwardly tapered, said mandrel being freely rotatable in said sleeve, and a nut in engagement with said mandrel thread, said nut and said sleeve including peripherally interengaging portion-s whereby said nut is held to said sleeve in the axial direction but free to rotate with said mandrel relatively to said sleeve.

2. A tool of the type described comprising a mandrel having one longitudinally slotted end portion, a screw threaded median portion, and another end portion adapted for the application of a torque, a nut adjustably engaging said mandrel thread, means to secure said nut to said i mandrel in an adjusted position, a sleeve with an interior cylindrical bore surrounding said mandrel intermediate its ends, said mandrel being axially shiftable and freely rotatable in relation to said sleeve, the sleeve end face adz jacent said slotted mandrel end including a portion tapering towards the other sleeve end, and means in connection with said other sleeve end and said nut to secure said nut to said sleeve against relative axial movement but with freedom to rotate with said mandrel relatively to said sleeve.

3. A tool as claimed in claim 2 wherein said cylindrical bore of said sleeve includes a rst portion of a diameter corresponding to the outer di- `ameter of said threaded mandrel portion which is freely movable therein axially and peripherally, and a second portion of a diameter corresponding to that of said slotted mandrel portion which is guided therein.

4. A tool as claimed in claim 2, said nut being provided with a peripheral groove in its portion adjacent said sleeve, and the sleeve and adjacent said nut including an axially projecting rim surrounding said nut portion and having its end turned into said groove of said nut.

5. A tool as claimed in claim 1 further comprising a prewinder device and means to attach said device releasably to said sleeve, said device comprising a cylinder surrounding said sleeve so as to permit axial and peripheral movement of said sleeve within said cylinder, said cylinder including a bottom provided with an opening through which the slotted mandrel end and the adjacent end portion of said sleeve can be projected, and a foot part connected to said cylinder at a distance from said cylinder bottom, said foot part being provided with an interior tapering thread co-axial with said cylinder and having its widest end on the side facing said cylinder bottom, and said foot also having an abutment face surrounding said widest end of said tapering thread to be engaged by the end face of said sleeve when the latter is shifted in said cylinder so as to project from said bottom.

6. A tool as claimed in claim 5, said means for attaching said device comprising an open end of said cylinder opposite said bottom and provided with an interior peripheral groove, a spring ring within said groove so as to project peripherally from said groove beyond the inner face of said cylinder, and oppositely directed and spaced frustro conical portions of said sleeve, adapted to expand said spring ring when engaging it upon axial shifts of said cylinder in relation to said sleeve.

7. A tool as claimed in claim 5, further comprising a piece inserted into a bore of said foot and secured to the latter, said piece being provided with said tapering thread and said abutment face.

JOHN O. FORSTER.

REFERENCES CITED The following references are of record Ain the le of this patent:

UNITED STATES PATENTS Number Name Date 1,418,298 Gorman June 6, 1922 2,050,702 Jackson Aug. 11, 1936 2,316,231 Evan Apr. 13, 1943 2,513,792 Forster July 4, 1950 

